Hi,
I am trying my best to explain difference between projection and aggregation in simple words.
Projection : It is use to select data without aggregation. NO Group By Clause. You will get entire dataset for selected columns.
Aggregation : Group by clause will be used here. So, you will get less number of rows in output.
Example :
I have create calculation view using below dummy table.
Modeling using Projection node :
Output of Projection_1 node :
( After activation, right click on Projection_1 node and select Data Preview. Same is applicable to Aggregation_1 node)
Modeling using Aggregation :
Output of Aggregation_1 node :
Conclusion : Using projection, we got 7 rows and using Aggregation, we got 2 rows. So, Using aggregation you are passing less data to another node. So, execution time will be fast.
Note : You will get same output at semantic layer for Projection and Aggregation.
Regards,
Vikram Divekar